[修电脑]开机后黑屏

mingo

操作系统为 win 7 ultimate
症状为

更新了一堆系统更新(windows update)后  开机进入windows, 在welcome过后出现黑屏, 屏幕上仅留有鼠标
使用safe mode后也是同样问题,  过了welcome后黑屏.
似乎是login之后的问题, 在welcome时Ctrl+alt+delete还能显示lock computer, switch user, logoff,  task manager.    点switch user / logoff  停留在login前的状态,正常.    点task manager 后无反应.  
如果是进入黑屏幕的状态下,  Ctrl+alt+delete 会出现  
Failure to display security and shut down options
The logon process was unable to display security and logon options when CTRL+ALT+DELETE was pressed. If the operating system does not respond, press ESC or restart the computer by using the power switch.

在safe mode + command prompt下会出现
cmd.exe application error
The application was unable to start correctly (0xc0000142)

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看了网上的一般解决黑屏方法, 都是需要task manager + cmd.exe

求 高手帮忙,  多谢.